通过HttpModule自动在Url地址上添加参数

由于项目中有许多页面需要用到cid参数，所以想通过传值cid来获取数据。

然而手机客户端又不支持Session和Cookie传值，

其他方法给页面赋值再传值显得太麻烦了，而且还不易维护，容易弄丢出错，

于是想到了用HttpModule来把cid参数赋在Url地址上，

让url把cid参数每页自动传递下去，需要用cid时只要通过Requet["cid"]获取,

这样就不用为传值而烦恼了。

 以下是配置方法和源码。

1）在web.config配置文件中添加以下节点

 

<httpModules>
      <add name="HttpModule" type="ThreeHegemony.Utility.AutoAddCid"/>      
</httpModules>

 

 

 

2）通过继承IHttpModule来实现url传值。

 

using System;
using System.Text;
using System.Web;
using System.IO;
using System.Text.RegularExpressions;

namespace ThreeHegemony.Utility
{   
    /// <summary>
    /// Auther:      Jess.zou
    /// Create data: 2009-08-06
    /// Description: 该类作用在Url地址后自动添加(cid)
    /// </summary>
    public class AutoAddCid : System.Web.IHttpModule
    {
        public void Init(HttpApplication context)
        {
            context.PostRequestHandlerExecute += new EventHandler(this.OnPreSendRequestContent);
        }

        protected void OnPreSendRequestContent(Object sender, EventArgs e)
        {
            System.Web.HttpApplication myContext = (System.Web.HttpApplication)sender;
            myContext.Response.Filter = new AppendSIDFilter(myContext.Response.Filter);
        }

        private void ReUrl_BeginRequest(object sender, EventArgs e)
        {
            string cid = "";
            string url = "";
            HttpContext context = ((HttpApplication)sender).Context;
            if (string.IsNullOrEmpty(context.Request.QueryString["cid"]))
            {
                if (context.Request.QueryString.Count == 0)
                {
                    url = string.Format("{0}?cid={1}", context.Request.RawUrl, cid);
                }
                else
                {
                    url = string.Format("{0}&cid={1}", context.Request.RawUrl, cid);
                }
            }
            context.RewritePath(url);
        }

        public void Dispose() { }

        public class AppendSIDFilter : Stream
        {
            private Stream Sink { get; set; }
            private long _position;
            private System.Text.StringBuilder oOutput = new StringBuilder();

            public AppendSIDFilter(Stream sink)
            {
                Sink = sink;
            }

            public override bool CanRead
            {
                get { return true; }
            }

            public override bool CanSeek
            {
                get { return true; }
            }

            public override bool CanWrite
            {
                get { return true; }
            }

            public override long Length
            {
                get { return 0; }
            }

            public override long Position
            {
                get { return _position; }
                set { _position = value; }
            }

            public override long Seek(long offset, System.IO.SeekOrigin direction)
            {
                return Sink.Seek(offset, direction);
            }

            public override void SetLength(long length)
            {
                Sink.SetLength(length);
            }

            public override void Close()
            {
                Sink.Close();
            }

            public override void Flush()
            {
                Sink.Flush();
            }

            public override int Read(byte[] buffer, int offset, int count)
            {
                return Sink.Read(buffer, offset, count);
            }

            public override void Write(byte[] buffer, int offset, int count)
            {
                if (string.IsNullOrEmpty(HttpContext.Current.Request["cid"]))
                {
                    Sink.Write(buffer, 0, buffer.Length);
                    return;
                }

                string content = System.Text.UTF8Encoding.UTF8.GetString(buffer, offset, count);

                Regex regex = new Regex(RegexResource.HREF, RegexOptions.IgnoreCase);
                Regex action_regex = new Regex(RegexResource.ACTION, RegexOptions.IgnoreCase);

                if (regex.IsMatch(content))
                {
                    content = Regex.Replace(content, RegexResource.HREF, new MatchEvaluator(ReplaceSID), RegexOptions.Compiled | RegexOptions.IgnoreCase);
                }

                if (action_regex.IsMatch(content))
                {
                    content = Regex.Replace(content, RegexResource.ACTION, new MatchEvaluator(ReplaceSID), RegexOptions.Compiled | RegexOptions.IgnoreCase);
                }

                byte[] data = System.Text.UTF8Encoding.UTF8.GetBytes(content);
                Sink.Write(data, 0, data.Length);
            }

            public static string ReplaceSID(Match match)
            {
                if (match.Value.IndexOf("cid=") != -1)
                {
                    return match.Value;
                }

                string result;

                if (match.Value.IndexOf('?') == -1)
                {
                    result = match.Value.Insert(match.Value.Length - 1, "?cid=" + HttpContext.Current.Request["cid"]);
                }
                else
                {
                    result = match.Value.Insert(match.Value.Length - 1, "&amp;cid=" + HttpContext.Current.Request["cid"]);
                }

                return result;
            }
        }
    }
}